1. Field of the Invention
This invention relates to sealing rings for rotary shafts and more particularly to sealing rings that are mounted obliquely on rotating shafts or in bearing surfaces surrounding such shafts to provide a greater sealing area on the shaft.
2. Description of the Prior Art
Rotary shafts are typically sealed with a conventional U-cup packing which is usually positioned so as to be perpendicular to the longitudinal axis of the shaft. In this orientation, the seal contact is limited to a narrow line on the shaft and the heat generated by the seal lip pressure and the shaft surface speed is confined to this small area. This heat is capable of quickly destroying the seal lip making the seal ineffective. One approach to alleviate this problem is to mount the seal obliquely with respect to the longitudinal axis of the shaft thus spreading the seal contact line over a much broader area. In this manner the heat generated is spread over a much greater surface area resulting in a much slower rate of heat buildup and a lower overall temperature increase. A seal mounted in this manner has a longer life and can be exposed to higher surface speeds and lip pressure. The primary disadvantage of this approach is that U-cup seals molded as conventional (planar) seals, i.e., where the plane of the seal is perpendicular to the longitudinal axis of the seal, and subsequently mounted obliquely on a rotary shaft do not have their sealing lips in the proper orientation with respect to the shaft to effectively seal same. Because of this lack of proper orientation, such oblique mounting of seals has been limited primarily to O-rings. To obtain the proper orientation of the seal lips, a U-cup seal with a non-planar configuration, i.e., where the plane of the seal is at an oblique angle with respect to the longitudinal axis of the seal, is required. The tooling costs for such a non-planar seal, however, are prohibitive.
Because of this, it has become desirable to develop a U-cup seal suitable for oblique mounting on a rotary shaft.